Gas turbine engines, such as those which power aircraft and industrial equipment, employ a compressor to compress air that is drawn into the engine and a turbine to capture energy associated with the combustion of a fuel-air mixture. One or more fluids are typically circulated throughout the engine. For example, oil may be supplied to one or more bearings in order to clean, cool, and lubricate the bearings.
Referring to FIG. 2A, the fluids are typically conveyed from a fluid source (e.g., an oil tank) 202 to the intended destination (e.g., the bearings or an associated bearing compartment) 206 by a supply tube 210. The fluid is then returned from the destination 206 to the source 202 by a return tube 214. In this manner, a closed-loop system 200 is established. There may be other components included; the system 200 is simplified for the sake of illustrative convenience. These other components may include additional tubes beyond the tubes 210 and 214.
Referring to FIG. 2B, in order to enhance reliability and avoid a leak impacting the performance/operability of the engine, the tubes (e.g., the tube 210 or the tube 214) may be manufactured as a double walled tube, where the fluid is intended to be conveyed by a first tube 232. A second tube 236 serves to contain any fluid that may leak from the first tube 232. The double walled tube arrangement shown in FIG. 2B is frequently referred to as a “tube within a tube” as the tube 236 has a larger dimension/diameter than the tube 232 and the tube 232 is contained/nested within the tube 236. In this respect, the tube 232 is an inner tube relative to the outer tube 236.
Referring to FIG. 2C, a system 250 is shown. The system 250 is shown as including five tube assemblies, denoted as assemblies 251, 252, 253, 254, and 255 (it is noted that the assemblies 252 and 253 may be implemented as a single assembly, resulting in four tube assemblies in FIG. 2C; for purposes of this disclosure, this distinction is of no import and is ignored going forward). Each of the assemblies 251-255 may correspond to a double walled arrangement as shown in FIG. 2B.
As shown in FIG. 2C, the assemblies 251-255 are separated from one another by hardware 261, 262, 263, and 264. The hardware 261-264 may support the assemblies 251-255 and provide a location for clamping the tube assembly and mounting the tube assembly to an engine structure (e.g., an engine case). The use of the hardware 261-264 represents a penalty/cost in terms of weight and complexity. The hardware 261-264 can also weaken/compromise the assemblies 251-255 (e.g., the tube 232 of FIG. 2B) at the point where the hardware interfaces to the assemblies.